Telemetric system



as" au G. M. GIANNINI ETAL TELEMETRIC SYSTEM Filed Oct. 29, 1945 llll May 18, 1948.

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G. M. GlANNlNl ETAL TELEMETRIC SYSTEM 2 Sheets-Sheet 2 Filed Oct. 29, 1945 Jasznb ani/d2' Patented May 18, 1948 UNITED STATES PATENT oFFlcE TELEMETBIC SYSTEM Gabriel M. Giannini, West Los Angeles, and Joseph F. Manildi, Pasadena, Calif., assignors, by mesne assignments, to Howe & Fant, Inc., South Norwalk, Conn., a corporation of Dela- Ware Application October 29, 1945, Serial No. 625,384

' (ci. 1v1-aso) 2 Claims. 1

to overcome the diiculties and shortcomings of the previous system, and, in general, to provide an improved transmitter for use in telemetric systems, which gives such a system greatly increased operational efilciency and operational characteristics which' are more exibly controllable by design selections. In telemetering systems the matter of high eniciency and also the one direction or the opposite, dependent upon the sign of the impulse or impulses received, The system is in essence a step by step system, in which the receiver is actuated in consonance with' the initial actuation of thetransmitter, so that the receiver may act as a remote indicator or as a remote actuating motor in a system of remote control.

In the system as described in the prior application, both the transmitter and the receiver instrument involve magnetic circuits including a movable magnet. In the transmitter instrument the movable generating magnet is actuated by a magnetic ratchet mechanism which' has the function of moving the generating magnet slowly in a direction which depends upon the direction of initial actuation of the transmitter, and then of releasing the moving generating magnet to be quickly snapped'back vto its initial position by magnetic forces. The rapid change in magnetic ux during the rapid back movement of the generating magnet, lgenerates an electric pulse of short duration in a generating coil associated with the magnetic circuit.

In the receiver instrument of the Giannini application a moving magnetized armature is utilized, that armature being moved selectively in opposite directions from a normal central position by opposite polarizations of an electro-magv netic circuit which isenergized by the received pulses.

Certain practical difficulties have been found in the described system. Without going into detail. it has been found that the eiiiciency of the system is relatively low, due to the relatively large inertia of the moving parts and to the relatively large amount of energy which must be applied to the transmitter in order to provide a given amount of finally `delivered energy at th'e receiver. It has also been found that considerable energy is involved in the movement of the moving generating magnet to its neutral position, and that vthe forces involved in operation are quite variable and non-linear.

It is the general object of the present invention size and mass of the component parts are of extreme importance, particularly in situations where space is limited or where the power available for initial actuation is small.

The present. invention accomplishes its pur-- poses and objectives primarily by utilizing a movable coil in a magnetic circuit as the pulse generating means. Movable coils, being of neutral polarity when at rest, have no tendency in themselves to assume any particular orientation in the magnetic fields, and are therefore easily moved in those fields to set them for their fast pulse generating movement or to return them to central neutral positions. Their inertia is small, so that the energy involved in accelerating them to high velocities is relatively small. Thus, as will be shown, a typical moving coil system can be made 'to attain over-al1 eiiiciencies several times as great as the system utilizing moving magnets; and ,size for size or weight for Weight the moving coil system delivers several times as much energy at th'e receiver.

In a typical illustration of the present invention, the transmitter instrument may involve a rotatable coil of the DArsonval type in a permanent magnet circuit and a stationary core within the coil. Upon angular displacement cf the coil in either direction from its centralized neutral position in the magnetic circuit, and upon 1'e-1 lease of the coil from the displaced mechanism,

a spring element acts to drive the coil back to its normal central position at relatively high velocity, resulting in generation of a pulse of high amplitude and sh'ort duration. A ratchet mechanism of suitable type is utilized to initially displace the 'coil in either one drection or the other depending upon the direction ci initial actuation.

A telemetering system, in which the new transmitter is used preferably includesl a receiver, in which a similar movable coil and magnetic circuit are utilized, the coil driving a two-way ratchet mechanism which drives a driven member step by step in a direction dependent upon the direction of coil displacement. Any suitable two-Way ratchet mechanism may be utilized; for instance, such a mechanism as is shown in the previous application referred to, or such a one as is shown by way of illustration in this present application. We make herein no claim to the ratchet mechanism in and of itself. The particular mechanlsm herein shown by way of illustration is the subject-matter of a copending application, Ser. No. 625,257, filed October 29, 1945, by Walter B. Claus.

In the following detailed description we set out preferred and illustrative forms of the new transmitter, referring for that purpose to the accompanying drawings in which- Fig. 1 is a central longitudinal section showing a typical form of the new transmitter instrument;

Figs. 2, 3 and 4 are sections taken as indicated by lines 2-2, 3--3 and 4 4 on Fig. 1;

Fig. 3a is a fragmentary illustration of parts shown in Fig. 3, with the parts in another position;

Fig. 5 is a diagrammatic perspective illustrating the essentials of a typical form of receiver instrument, and

Fig. 6 is a diagram illustrating the circuiting i of the system.

Figs. 1 to 4 are on a scale twice the size of the actual instrument for which some typical figures are given hereinafter.

In the illustrative form of transmitter instrument shown in Figs. 1 to 4.- a toroidal coil IU of rectangular formation is carried at one end 4by a shaft and at the other end by a short stub shaft I2. These two shafts are journaled in bearings in bracket members I3 which form a part of the framing of the instrument. The coil is preferably formed of enameled wire set in a plastic cement o1' other composition to make it rigid without the necessity of using a separate frame. Connections to the coil may be made in any usual manner, spiral connector members being shown at I4. The outer end of one of these spiral connectors may be directly grounded to the frame, as is shown for the lower connector in Fig. 1. The other connector I4 may be connected with an insulated terminal, such as that shown at I5. Another grounded terminal is shown at I5a.

Coil I0 rotates in the air gap between two pole pieces 20 and an internal stationary core 2| which is mounted on the two bracket members I3 as shown in Figs. 1 and-2. The two bracket members I3 are mounted upon a main framing member 22. Pole pieces 20 form parts of a permanent magnetic circuit which is made up of the pole pieces, two permanent magnets 25 and a yoke 26. The physical arrangement of the parts of the magnetic circuit with relation to the other parts of the mechanism may be as desired; the arrangement shown in the drawings is merely illustrative.

Coil I0 normally occupies a central neutral position such as shown in Fig. 2 and is yieldingly held in that position by a pair of springs 30 which are mounted at one end in a block. I3a, and whose free ends are adapted to press oppositely upon a flat block 3| set on coil shaft II. In the normal or neutral position block 3| lies flatly between the two springs 30, and when the shaft and coil are displaced in either direction, the springs tend to force them back to the normal position. The action of such a spring system on a fiat block tends to be self-damping, so that the oscillations of the shaft and coil, after being forced back to normal position at high velocity, are small. Those oscillations are further minimized by a stop block |3b interposed between the ends of springs 30 and of such width that the springs close down on that block just before block 3| reaches its central position. That is, when at rest in central neutral position (Fig. 3) the swinging block 3| is decoupled from the springs, and the two springs are decoupled from each other. Thus, as the system reaches the neutral position of Fig. 3 direct impact occurs between the springs and block |3b, dissipating a considerable portion of the'energy in the spring and decoupling the spring momentum from the swinging block 3l.

The forces exerted by springs 3U, and therefore the torque exerted onl the coil shaft, may be at least roughly determined by size and design of the springs and by the dimensions of block 3|. A suitable means may be provided for further adjusting the spring pressures, as for instance the adjustment screws which are shown at 33,

The means for displacing the coil from its normal neutral position is here shown as embodying a pawl 35 set on the lower end of coil shaft I, and a star wheel 36 mounted on a shaft 31. In the normal neutral position the outer pointed end of pawl 35 lies on a radial line between shaft 31 and shaft II, and in a position to be engaged by teeth 38 of the star wheel when that wheel is rotated in either direction. In the particular design here shown the parts are so dimensioned and related that pawl 35 and the coil I0 are swung through an angle of about 34 to one side of the neutral position when a tooth passes under the pawl. Figs. 3 and 3a illustrate for instance the action when star wheel 3G is rotated counter-clockwise as seen in those figures. Fig. 3a. shows approximately the position of maximum coil displacement, with a tooth 38 wiping under the end of the pawl. Upon further movement of the tooth counter-clockwise the pawl is released and springs 30 immediately force the pawl and coil back to the neutral position of Fig 3. Star Wheel teeth 38 are spaced far enough apart that the next oncoming tooth is not immediately contacted bythe pawl when it reaches its neutral position. It will be understood that in the normal operation of the transmitter mechanism star wheel 36 is rotated relatively slowly, so that the velocity of coil movement during the initial displacement is relatively low as compared with the high velocity of return movement of the coil under the action of springs 30. The latter movement, in the present specific and illustrative design, is designed to occur in about 1/100 of a second.

Upon slow displacement from normal position to the position of Fig. 3a the current generated in the coil is negligible. Upon rapid return to the normal position, a pulse of high amplitude and short duration is generated, with the current flowing in a determined direction. Continued counter-clockwise rotation of star wheel 36 at relatively low speed will cause the generation of a series of spaced impulses each of high amplitude and short duration and all of the same sign. Rot-ation of the star wheel clockwise will cause similar pulse generations of the opposite sign, as will be clear without detailed description,

Star wheel 36 or its shaft 31 may be driven directly, either manually or from any mechanism or device. Or, in some installations it may be driven through a gear train such as is illustrated in the drawings. As there shown a shaft 40 is the initially driven shaft of the instrument and gears 4| interconnect shaft 40 with star wheel shaft 31. Where a gearing train or any other driving train with loose play is used between the initial driver and the star wheel shaft, a spring may be applied to the star wheel shaft to keep the driving train tight at all times and to eliminate the looseness which would otherwise occur by.blacklash. Such a spring is shown at 45 in the form of a spiral spring having its innerV end attached to shaft 31. Spring 45 acts upon shaft 31 in such a direction as to keep tight all of the motion transmission parts between the star wheel and the device or mechanism which initially drives the instrument; if those transmission parts are wholly composed of gearing, spring 45 vmay act upon the star wheel shaft tending to drive it in either direction, so that backlash is taken up 'in the selected direction. And to keep the back lash closed, spring 45 is designed to exert a sufclent torque on shaft 31 to overcome frictional losses inthe driving train and also to supply the energy which is necessary to displace pawl 35 against theaction of springs 30, when the star wheel isrotating in the direction in which spring 45 tends to'drive it.

A typical receiver suitable for use with the ne transmitter is shown'merely diagrammatically in As there shown the moving coil is mounted on a shaft I l to rotatein the field between two pole pieces 20 of a magnetic circuit which may be and preferably is the same in essentials as shown in Fig. 1 and preferably includes a core such as shown in Fig. 1. In fact, the magnetic circuit, the coil and its mountings, may preferably be duplicates in the transmitter and receiver of the system. The normal or neutra-l position of the coil in the magnetic field is such as thatshcwn in Fig, 5. Connections to the coil may be made as'shown in Fig. 1, being shown merely diagrammatically at |09 in Fig. 5. Fig. 6 illustrates diagrammatically the circuiting of the transmitter-receiver system, showing a two-wire circuit at |00. One side of the circuit can be grounded so that only one wire is used.

As illustrated in Fig. the coil shaft ||0 carries a double-ended pawl arm I3 affixed to it, and pawls ||4 are pivotally attached to the ends of that arm and project toward a toothed ratchet wheel |20 so that their free ends ||4a lie just under two teeth l20a. These two teeth |20a are not di-ametrically opposite each other but, as shown in Fig. 5 are locater1 on that side of wheel |20 which faces the pawl arm H3. Pawls ||4 are guided by a pair of fixed stop pins l5 which limit their inward movement toward each other so that each pawl will clear the tooth which lies in the position indicated at |20b. Springs H5 press pawls ||4 against stop pins H5. A pair of centering springs Il'l are shown as acting upon a pin H8 which is set in arm H3; the action of these springs H1, taking pin I0 and shaft ||0 between them, being much like the action of springs 30 0f Fig. 1 on the flat block 3|. A detent spring |25 engages the ratchet wheel to hold its teeth normally in the relative position shown in Fig. 5. A pair of stop pins |30 may be used tov limit the swinging movements of pawl arm H3.

The various moving parts of the receiver mechanism, particularly the pawl arm H3 and pawls ||4 may be constructed very lightly and to have a small inertia. The coil may be and preferably is constructed and mounted in the same manner as that which has been explained in connection with Fig. 1. A specifically illustrative design for the ratchet mechanism and for the whole receiver is shown, for instance, in the copending application of Walter B. Claus before referred to.

pressed on coil Il I, the coil will swing in a predetermined direction in the magnetic field. swinging arm Il; with it. Assume for instance that the arm swings clockwise in Fig. 5. Left hand pawl ||4 moves upwardly into engagement with left hand tooth |a andmoves that tooth upwardly through a predetermined distance which is preferably equal to the spacing between teeth. Simultaneously the right hand pawl III moves down aheadof the right hand tooth |20a, and

moves out of the way of that tooth so that it can move forwardly to the position previously occupied by the right hand tooth |2011. Upon cessation `oi.' the pulse, centering springs `Hl return the pawl mechanism and coil to normal central Y position, the left hand pawl'i I4 dragging downwardly over the tooth which has taken the position of |20b, and the right hand pawl I|4 moving upwardly Vand clearing thel tooth which then stands in the position |201). When a pulse of the opposite sign is impressed upon the coil, the coil and the pawl arm swing in the opposite direction. resulting. in the rotation of `ratchet wheel |20 through a distance 'of one tooth in the opposite direction.f

In a transmitter instrument such as shown in Fig. 1, where the coil isabout 0.9 in. long and 0.45

.in. wide, wound with 180 turns of No. 38 enameled wire set in plastic, the moment of inertia is very lowabout 02x10*8 in. lb. sec?. With springs 30 of such strength as to apply 0.01 in. lb. to the coil per radian of its rotation, the period of the system is about 0.028 sec. and the time period for spring actuated return of the coil through 34 is about 0.01 sec. Low inertia minimizes the energy required, and the high speed of actuation maximizes the amplitude of the generated pulse. -In the particular instance for which these figures are given, and where the receiver coil and magnetic circuit are duplicates of those of the transmitter, with field intensities of` about 4000 gauss, the torque delivered by the receiver is as much as 0.0023 in. lb. for a 34 angle of swing of the transmitter and receiver coils. The torque generated by the transmitter, and that finally delivered by the receiver coil, are relatively high for instruments of the size under consideration. And the maximum' initial torque which must be applied to the transmitter is only 0.006 in. lb.; so that the over-all efilciency is about 38%. The high amplitude and short duration of the pulse delivered by the transmitter,

. and the high action speed of the receiver, also given, that frequency can be as high as about 20 per second. We claim:

1. A transmitter for telemetric systems comprising a magnetic circuit including an air gap, a coil mounted forV rotary current-generative movement in the air gap, a stationary core within the coil, elastic means normally holding the coil with its plane normal to the magnetic lines in the gap and acting to return the coil to normal position after displacement therefrom in either direction, said means comprising a :dat block coupled with the coll for rotation therewith and a pair of flat springs pressing on 4opposite faces of the block, a driving member indefinitely rotatable in either of two'opposite directions, and ratchet means adapted to cause successive displacements of the coil in a direction dependent upon the direction of rotation of the driving When a pulse of a predetermined sign is im- ,75 member,

2. A transmitter for telemetric systems comprising'a magnetic circuit in-cludingan air gap, a. coli mounted for rotary current-generative movement in the air gap, a stationary core within the coil, elastic means normally holding the coil with its plane normal to the magnetic lines in the gap and acting to return the coil to normal position after displacement therefrom in either direction, said means comprising a flat block coupledwith the coiifor rotation therewith and a pair of flat springs pressing on opposite faces of the block, a driving member indenitely rotatable in either of two opposite directions, ratchet means adapted to cause successive displacements of the coil in a direction dependent upon the direction of rotation of the driving member and tending to drive it in one direction with energy at least sufficient to actuate the coil displacement means.

GABRIEL M. GIANNINI. JOSEPH F. MANILDI.

8 REFERENCES CITEDl The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name y Date 1,278,949 Le Compte Sept. 17, 1918 1,657,587 Pupin Jan. 31, 1928 1,755,340 Sperry Apr. 22, 1930 1,926,316 Stafford Sept. 12, 1933 2,293,166 Olson Aug. 18, 1942 2,330,801 Abbott Oct. 5, 1943 2,396,244 Borsum Mar. 12, 1946 FOREIGN PATENTS Number Country Date 515,212 Great Britain Nov. 29, 1939 

